This application claims the benefit of a Japanese Patent Application No. 2002-112247 filed Apr. 15, 2002, in the Japanese Patent Office, the disclosure of which is hereby incorporated by reference.
1. Field of the Invention
The present invention generally relates to substrates, connecting structures and electronic equipments, and more particularly to a substrate which uses an electrical connecting body such as a flexible printed circuit (FPC), a connecting structure which uses an electrical connecting body such as the FPC and is suited for connecting a main body and a lid which opens and closes with respect to the main body, and an electronic equipment having such a substrate or connecting structure.
In this specification, the electronic equipment refers to information processing apparatuses such as a lap-top personal computer, portable telephones and the like which are made up of a main body and a lid which opens and closes with respect to the main body.
2. Description of the Related Art
For example, the lap-top personal computer is made up of the main body and the lid which opens and closes with respect to the main body. A substrate mounted with various parts such as integrated circuit devices (IC chips) is provided within the main body, and a display section made up of a liquid crystal display (LCD) or the like is provided within the lid. Because the lid opens and closes with respect to the main body, the display section and the substrate are electrically connected via the FPC. One end of the FPC is connected to the display section, and the other end of the FPC is connected to a connecting part which is provided at an end portion on the substrate. The connecting part is connected to the electronic parts such as the IC chips on the substrate via a printed wiring formed on the substrate.
The printed wiring on the substrate may be provided on both top and bottom surfaces of the substrate but the printed wiring must be arranged avoiding positions where the various parts are mounted on the substrate and positions where holes and cutouts are formed in the substrate. Signals supplied to the display section employ the LVDS system or the like, and are high-speed and small-amplitude signals. Hence, the substrate must satisfy various layout and wiring conditions, such as limited wiring length and wiring layout for preventing mixture of external noise. Accordingly, depending on the layout and wiring conditions, it is necessary to take measures such as arranging the IC chip for driving the display section in a vicinity of the connecting part on the substrate, and arranging the printed wiring on the substrate at a position separated from other printed wiring for the high-speed signals.
Recently, due to increased operation speeds of internal circuits of the CPU or the like, heat generated from the IC chips mounted on the substrate has become large. For this reason, it has become necessary to provide holes and cutouts in the substrate, and to provide radiator parts or heat sinks at the holes and cutouts so as to improve the heat radiation or heat release from the IC chips. In order to improve the heat radiation, the radiator parts must be made large, which means that the corresponding holes and cutouts in the substrate must also be made large. The printed wiring on the substrate must be arranged avoiding these holes, cutouts and radiator parts.
On the other hand, in order to meet the demands to further reduce the size of the lap-top personal computer, gaps or spacings between the parts mounted on the substrate are becoming smaller. As a result, the degree of freedom of wiring is decreasing for the printed wiring on the substrate.
It is conceivable to provide a multi-layer (or multi-level) wiring structure on the substrate, but the structure of the substrate will become complex. In addition, as the multi-layer wiring structure itself and the connections of the various wiring layers and the electronic parts such as the IC chips become more complex, the assembling process becomes complex, to thereby increase both the production cost of the substrate and the thickness of the substrate. Hence, it is difficult to realize a thin lap-top personal computer using the substrate having the multi-layer wiring structure.
Therefore, in the conventional electronic equipment, there are problems in that it is difficult to conform to the various restrictions with respect to the printed wiring on the substrate, secure a relatively large degree of freedom of wiring, and electrically connect a portion on the substrate and another portion, while simultaneously meeting the demands to reduce both the cost and size of the electronic equipment.